The art is replete with scanning systems for scanning a light image in order to reproduce the same as in a camera or reproduction machine both of which are generically identified as copiers. In such copiers a photographic lens projects the image either from or to a film plane with a document disposed at the folded document plane at any magnification ratio. In a duplicator the document is a moving photoconductor, be it a drum surface, a belt, or a moving coated receptor sheet. In a camera the document is an original document moving past the exposure aperture on a drum, a belt or transparent support.
Moving mirrors have been used to scan stationary original images to direct segments of the images successively onto the receptor. One such patent is U.S. Pat. No. 3,966,319, issued June 29, 1976 to J. M. Lang. This patent discloses a movable mirror which scane one axis of the image, and the mirror is shifted in opposite directions tranverse to its pivotal axis and is simultaneously rotated about its axis in one direction during a scanning cycle to scan a stationary document. The scan across the Y axis or length dimension of a flat field is controlled and the length of the optical path is maintained constant during the scan. This structure differs from that of the present invention in that the mirror only moves on one side of the optic axis while changing its angle to direct the beam from one side of the flat field "Y" dimension to the other side. Thus this patent does not teach imaging by conventional photographic optics a full flat field (X and Y dimensions), nor does it teach the scanning of a microform image plane by a single mirror scan where the optical path length is changing by the amount given by the expression ##EQU1## wherein F=the focal length, M=the enlargement ratio and u'=one-half the flat field angle. Thus the scanning of the image by shifting the mirror along the axis of the reflected ray while rotating it in a single direction to scan the flat plane differs from the idea of moving the mirror along one coordinate and shifting the angular position of the mirror to move the image along the surface of the mirror to scan the image as taught by the invention of applicants.
Other prior art teaches the rotation of a mirror which receives the reflected image from a scanner of a fixed object to merely direct the image to a lens or onto the receptor surface. Other prior art using pivoting mirrors scan curved focal planes, thus compensating for the changes in distances of the image points from the document surface to avoid keystoning or other distortions of the image when reproduced on the receptor.
The present invention provides a method and apparatus for directing image points to or from a film plane from or to a folded plane so corresponding image points on the folded document plane are synchronized with corresponding points on the normal document plane. Various magnifications can be accommodated by merely changing the lens of the system.